Ever since the disappointment of Copenhagen three years ago, the annual rounds of climate negotiations have prompted a familiar chorus of cynicism and hand-wringing. But last year in Durban, largely freed from the burden of high expectations, governments agreed to adopt a universal and legally binding agreement on climate change no later than 2015.

The plan is to ensure that this will be implemented by 2020 and this timeline is critical if we are to give ourselves more than a 50% chance of avoiding a temperature rise of more than 2C. But as a recent PricewaterhouseCoopers report highlights, the reality is that we should start planning for a world that is 4C or even 6C warmer.

To achieve this ambition effectively means that the world needs to reduce its carbon intensity by more than 5% each year – a degree of de-carbonisation not achieved in any year since the second world war. We are playing high stakes poker in the last chance saloon.

The latest negotiations that kick off in Doha on Monday offer a glimmer of hope which we must make the most of. The focus of the agenda will be on how to operate and implement much of what has already been agreed on technology transfer, financing and adaptation. Most importantly it will set the negotiation parameters that will help forge an international deal in 2015. The challenge will be for business leaders to demonstrate how they are part of the solution, not the problem.

Business has a critical role to play in the transition to a low carbon economy: in innovating and investing in the new technologies and systems that will form its foundation, and engaging and educating consumers in sustainable living and how making small everyday decisions can make a big collective difference.

Business voices can also support and influence the design of the policy response and institutional architecture that together will underpin the transition. We need to showcase the art of the possible rather than highlighting what the obstacles and challenges are. At Unilever, we have set ourselves the ambitious target of reducing our greenhouse gas emissions by 50% across our entire value chain by 2020 – a target which is comparable to that being mooted on the international stage.

Too often, the business voices that whisper to politicians in private or shout in public are those who are opposed to ambitious action on climate change. They see the writing on the wall for the old ways of doing, but are determined to ignore it. This strategy has outlived its usefulness.

Last year the impacts of climate change – primarily droughts and flooding – cost Unilever more than €200m (£162m). Even if you can ignore this, or put it down to a one-off, you cannot ignore the growth of social media, which will be ruthless to businesses that are judged to be making the world a worse place, not a better one.

So many companies are waking up and realising that they can be inside the tent, shaping solutions, future-proofing their businesses, strengthening their ties with their existing consumers and reaching new ones. We saw this at Rio+20, and I hope that we will see this at Doha too, with more concrete results.

I'd like to highlight two areas where we have a particular interest in progress at Doha:

•Carbon markets; already countries and regions as diverse as the EU, Costa Rica, Japan, South Korea and Australia have established or are establishing different forms of carbon pricing and trading mechanisms. There is even emergent interest in the US, where a combination of president Obama's re-election, the aftermath of superstorm Sandy and the prospect of the impending 'fiscal cliff' is encouraging policy makers to look at the option afresh.

Effective carbon pricing can mobilise finance at a scale that can impact the climate challenge, and better align the scale, reach and innovation of business with the needs of the planet and its growing population. This is why Unilever is an enthusiastic signatory to the Carbon Price Communiqué, which urges policy makers to introduce a clear carbon price framework in a stable and timely way.

We know that without proper pricing of externalities, including carbon and water, and an end to perverse subsidies that encourage the production and inefficient use of these resources, we will always face an uphill battle to persuade consumers to change their behaviour.

•Deforestation; another subject close to our hearts. As a member of the Consumer Goods Forum (CGF), Unilever has committed to achieving zero net deforestation in our supply chains for palm, soy, paper, beef and timber by 2020, and we work through multi-stakeholder bodies such as the Roundtable on Sustainable Palm Oil and the Forest Stewardship Council. We ask that governments work in partnership with us to address the complex and interlinked drivers of deforestation, and build frameworks to incentivise demand for sustainably-sourced commodities through preferential import and export tariffs and improved regulation.

Ultimately, whether business leaders are now convinced by the devastation on the US's east coast and Haiti, or by the latest reports by PwC and the World Bank, it doesn't matter. What matters is that they support, as vocally as they can, the progress we need to make in Doha.